theanswers · Mar 5, 2012

Hi,
I'm looking for a new gearbox auto for my p38. the old one gave up.

Will a gearbox from a 4.6 do? even if I change the bell housing or will only the 4.0/ 2.5 work?
It is a 2.5?
Regards,

wammers · Mar 5, 2012

theanswers said:
Hi,
I'm looking for a new gearbox auto for my p38. the old one gave up.

Will a gearbox from a 4.6 do? even if I change the bell housing or will only the 4.0/ 2.5 work?
It is a 2.5?
Regards,

Save yourself some bother and get one from a 2.5.

jamesmartin · Mar 5, 2012

you could use 4.6 one if you strip box and change cp shaft (input shaft)

wammers · Mar 5, 2012

jamesmartin said:
you could use 4.6 one if you strip box and change cp shaft (input shaft)

I somehow think the idea of fitting a 4.6 box will suddenly dwindle in importance.

Datatek · Mar 5, 2012

jamesmartin said:
you could use 4.6 one if you strip box and change cp shaft (input shaft)

Am I being dumb? Why would you have to change the input shaft? It only connects to the torque convertor

jamesmartin · Mar 5, 2012

because i replied with out reading thread and was thinking of a manual box from another thread a case off not looking before leaping

BAZZ · Mar 5, 2012

Hi there are several DIFFERANT types for the P38, both petrol and diesel. The petrol ones are not suitable for the diesel and visa-versa, because the valve block is set up differantly, as it changes gear at differant engine and road speeds.

Datatek · Mar 5, 2012

theanswers said:
Hi,
I'm looking for a new gearbox auto for my p38. the old one gave up.

Will a gearbox from a 4.6 do? even if I change the bell housing or will only the 4.0/ 2.5 work?
It is a 2.5?
Regards,

Fitting the box from a 4.6 is unknown territory. The bell housing would have to be swapped and so would the extension piece between the autobox and the transfer box as the ZF4HP24 from the 4.6 is longer than the ZF4HP22 from the diesel. I'd love someone to do it as it would improve the life expectancy of the box on the diesel and accomodate performance upgrades.
When my box finally fails it's something I will try, all the info I have found suggests it can be done but the only way to be sure is to try it

Datatek · Mar 5, 2012

BAZZ said:
Hi there are several DIFFERANT types for the P38, both petrol and diesel. The petrol ones are not suitable for the diesel and visa-versa, because the valve block is set up differantly, as it changes gear at differant engine and road speeds.

Ballcocks, it's the ECU that is different between the petrol and Diesel. there are only 2 types of box, ZF4HP22 for the diesel and the 4.0 and the ZF4HP24 for the 4.6. There are however 3 types of torque convertor and 3 or 4 types of ECU maybe more

jamesmartin · Mar 5, 2012

datatek do you have parts list for both boxes

6704nathan · Mar 5, 2012

iam sure i found an old thread once where someone had fitted 4hp24 box in a diesel and as i recall they said all they changed was the torque converter and bell housing from the diesel 4hp22 box?

Datatek · Mar 5, 2012

jamesmartin said:
datatek do you have parts list for both boxes

Regretably no, all I have done is researched the varients regarding length and the interchangeability of the bell housing and torque convertor. ZF confirmed that the 24 and the 22 are likely to be interchangeable as the control is the same but they wouldn't comment on the physical aspects.
I have a spare 22, but next time I'm in the UK I would like to pick up a good 24 and see what I can do

Datatek · Mar 5, 2012

6704nathan said:
iam sure i found an old thread once where someone had fitted 4hp24 box in a diesel and as i recall they said all they changed was the torque converter and bell housing from the diesel 4hp22 box?

Those two bits definately have to be swapped and should be compatable, but I have info that implies that the distance piece to the transfer box may also have to be swapped

It certainly looks do able

6704nathan · Mar 5, 2012

could you not just use the transfer box from the 24? as the box is longer use the propshafts from the 4.6 if they are shorter than on the diesel?
just a thought!!!

Datatek · Mar 6, 2012

6704nathan said:
could you not just use the transfer box from the 24? as the box is longer use the propshafts from the 4.6 if they are shorter than on the diesel?
just a thought!!!

Transfer box is apparantly the same, but easier to shove the complete lump in I guess. If all the parts are correct I think the diesel props should match up OK

jamesmartin · Mar 6, 2012

if rear housing is shorter so will be output shaft

Datatek · Mar 6, 2012

jamesmartin said:
if rear housing is shorter so will be output shaft

Fair enough. That's why it's difficult to judge what's needed. There are 3 bell housing types, the 4.6 being longer than the 4.0 or the diesel. two different gearbox lengths and two different spacers between the auto and the transfer box. The easiest way is with a pair of boxes side by side, but with the right selection of bits I'm guessing all the mountings and the props should line up.
It's possible that if the diesel bell housing is the same length as the 4.0, ie shorter than the 4.6 bell housing, that neither spacer will be right, in which case mods would be required.

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